Method of and apparatus for forming stacks of a preselected number of blanks

ABSTRACT

A method of and apparatus for forming a stack of corrugated paperboard blanks of preselected number comprising the steps of depositing such blanks sequentially into a first hopper forming a stack thereof; advancing a group of blanks of preselected number from the bottom of the stack and advancing the same into a second hopper; raising the group in the second hopper a sufficient distance to permit entry of a second group of blanks being advanced from the first hopper beneath the raised group in the second hopper; continuing this sequence until a final stack of blanks of preselected number is formed in the second hopper; then removing the final stack of blanks from the second hopper; and thereafter forming another final stack of blanks in the second hopper in the same manner. The apparatus for performing the method includes a first hopper with a first advancing conveyor on the bottom thereof; a gate for preventing advancement of the blanks in the hopper and to define a throat with the conveyor; a squaring assembly for squaring the blanks against the gate; the conveyor including advancing fingers for periodically removing a group of a preselected number of blanks from the bottom of the stack; a second hopper having an upstanding pivotable gate assembly for preventing advancement of the blanks in the second hopper; a second conveyor forming the bottom of the second hopper on which are secured lifting fingers for periodically raising the group of blanks in the second hopper to permit entry of another group of blanks from the first hopper beneath the raised group in the second hopper; and means for pivoting the pivotable gate assembly to permit the second conveyor to remove the final stack of blanks in the second hopper.

United States Patent 191 Primary ExaminerFrank T. Yost AssisrdmExaminer-fairies F. Coon Attorney-Boyce C. Dent, Oscar B. Brumbach andOlin E. Williams Lulie et al. [45] Jan. 23, 1973 [5 METHOD OF ANDAPPARATUS FOR ABSTRACT FORMING STACKS OF A A method of and apparatus forforming a stack of cor- PRESELECTED NUMBER OF BLANKS rugated paperboardblanks of preselected number 75 Inventors: Albert L. Lulie, Baltimore;Paul 1). P t the Steps fdepsittttg Such blanks Sequen-HarPerTimoniumboth of Md. tially into a first hopper forming a stackthereof; ad- 31 -g i b p y inc. vancmg a group of blanks of preselectednumber from 3 3 3 the bottom of the stack and advancing the same into a[22] Filed: Dec. 28, 1970 second hopper; raising the group in the secondhopper a sufficient distance to permit entry of a second group [211 App!101,501 of blanks being advanced from the first hopper beneath theraised group in the second hopper; conl l Cl 93/36 Q, 93/93 tinuing thissequence until a final stack of blanks of 9 /9 214/6 BA preselectednumber is formed in the second hopper; [51] Int. -@6 33/00 then removingthe final stack of blanks from the Field (Search Q, L M, second hopper;and thereafter forming another final 93 214/6 BA stack of blanks in thesecond hopper in the same manner. The apparatus for performing themethod in- 5 R f n Ci d cludes a first hopper with a first advancingconveyor on the bottom thereof; a gate for preventing advance- UNlTEDSTATES PATENTS ment of the blanks in the hopper and to define 212,886,929 5 1959 Villemont ..93/93 M thma with the Mayor; 3 squaringassembly 3,229,599 1/1966 Lowe 93 93 M Squatihg the blanks against thegate; the conveyor 3,442,186 5/1969 Himse et 3] 93 9 M eluding advancingfingers for periodically removing a 2,749,120 6/1956 Mallory 214/6 BAgroup of a preselected number of blanks from the bot- 1,627,79l 1927 y 8M tom of the stack; a second hopper having an upstand- 2,931,520 4/1960shieldsml SQ ing pivotable gate assembly for preventing advance- 3l642701/1965 l r "214/6 BA ment of the blanks in the second hopper; a second 3232 221 2/132: 31232;; 1912/2 :2 o W of o 9/1965 califano "j 'j M whichare secured hftmg fingers for periodically ra1s- 3,421,638 1/1969 Lockeet al. ..214/6 BA mg the gwuP 0f blattks the Second hopper Permit3,495,374 2 1970 Ebbers et al. .....214 6 BA entry of another group ofblanks from the first hopper 3,452,651 7/1969 Vadas ..93/36 so beneaththe raised g p in the second h pp r; n 3,550,493 12/1970 Benbenek et a1,..93/93 C means for pivoting the pivotable gate assembly to per-3,543,65l 12/1970 Donahue ..93/93 DP mit the econd conveyor to rem vethe final stack of 3,580,145 5/1971 Vermes ..93/93 DP blanks in theSecond hopper 30 Claims, 23 Drawing Figures I10 lanela: /4; M4 250 290PATENTEDJAN23 I975 3.712.186

SHEET 02 0F 10 m INVENTOR.

44554 71. 1114/5 6 BY PAUL .0. HAKPAIF PATENTEDJAN23 I875 3,712,186

SHEET 05 0F 10 PATENTEDJAM2I3 ma SHEET O80F 10 8523 vum IEEQ $m Kiwis su M m H P w 600 '60? 504 LAMPS T/MED CLOSING MAN, AUTO. 502

CL UTCH 524 6323 mi: N\ QWQQQI 4 r :w L a N 1 |1 4 H L a 7/02 m 6 Wm. a0 0m Em; 7 N W T TM 70 m I o 6 H H L MAN AUTO MAN. AUTO,

OPERATION MODE FIG. I5

INVENTORS $55974. 4114/5 F PAUL 0. HARPER PATENTEDJAH 23 I973 ll l L a/zINVENTORS ALBERTL. LUL/E a PAUL a. HARPER FIG. I6

METHOD OF AND APPARATUS FOR FORMING STACKS OF A PRESELECTED NUMBER OFBLANKS BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates generally to material or article handling and moreparticularly to article piling or arranging apparatus.

2. Description of the Prior Art The invention relates to stackingapparatus for receiving individual folded tubular blanks from afolder-gluer and for stacking the blanks into a final stack of apredetermined number of blanks for tying and shipping as a bundle.Blanks folded and glued in conventional folder-gluer machines oftenleave the folder-gluer machine in an out of square condition. Thiscondition, of course, must be corrected before the glue dries. It isdesirable to have these individual blanks piled in a final stack forsubsequent bundling. In view of floor space and material handlingconsiderations, it is also desirable to accomplish squaring and stackingin a straight line operation immediately following the folder-gluer. Itis additionally helpful to have the squaring and stacking accomplishedat substantially the same level that the blanks leave the folder-gluer.Since the folder-gluer is capable of processing blanks of various sizes,blank squaring and stacking machines must possess a capability forhandling runs of blanks whose dimensions may vary widely from run torun. Besides this, it preferably is adjustable to provide final stacksof blanks of preselected numbers for subsequent bundling preparatory toshipping.

SUMMARY OF THE INVENTION This invention provides a method of andapparatus for forming a final stack of blanks of preselected number. Thepreferred method comprises the steps of depositing individual blankssequentially'into a first hopper thereby forming a stack of blankstherein; advancing a group of blanks of preselected number, e.g.,blanks, from the bottom of the stack into a second hopper locateddownstream from the first hopper; raising the group of blanks in thesecond hopper, preferably by lifting the trailing edge of the group, asufficient distance to permit entry of another group of blanks from thefirst hopper beneath the lifted group in the second hopper; continuingthe foregoing steps until a final stack of blanks of preselected numbersis formed in the second hopper; and thereafter removing the final stackfrom the second hopper.

The apparatus used to perform the foregoing method generally includes apair of conveyors arranged in tandem along a generally horizontal pathbeneath a path of supply of such blanks such as from a folder-gluer. Agate assembly intercepts the flow of blanks arriving sequentially fromthe supply thereby causing the blanks to fall one at a time on top ofthe first conveyor thereby forming a stack of such blanks thereon. Asquaring plate is located adjacent the trailing edge of the stack; thesquaring plate is arranged to reciprocate against the trailing edge ofthe stack thereby urging the leading edge against the gate assembly forthe purpose of squaring the blanks. The first conveyor includes a pairof circumferentially spaced fingers for advancing a group of apreselected number of blanks from the bottom of the stack onto thesecond conveyor.

The second conveyor includes a pivotable gate assembly for interceptingthe flow of groups of blanks received from the first conveyor. It alsoincludes a pair of lifting finger assemblies circumferentially spacedaround the conveyor with each being arranged to lift the trailing edgeof the group on the second conveyor to permit entry of a second group ofblanks from the first conveyor beneath the lifted trailing edge. Thearrangement is such that the group of blanks on the second conveyor israised each time a group of blanks is received from the first conveyorthereby building a final stack of blanks on top of the second conveyor.When the stack on the second conveyor has attained a preselected numberof blanks, the pivotable gate assembly is pivoted to a horizontalposition thereby permitting the stack of blanks to rest on the rotatingsecond conveyor which then advances the complete stack downstream toanother conveyor or table or the like where the stack can be tied in abundle.

Provision is made for adjusting the length and width of both the firsthopper'formed over the first conveyor and the hopper formed over thesecond conveyor so that the machine is capable of forming stacks ofblanks whose dimensions vary from run to run.

Suitable counters are provided for counting the groups of blanks formedin the stack in the second conveyor and for energizing the pivotablegate assembly when the final stack contains the desired number ofblanks.

Detection devices are provided for maintaining the height of the stackof blanks on the first conveyor within predetermined limits to preventover filling or underfilling.

The above and further objects and novel features of the invention willappear more fully from the following detailed description when the sameis read in connection with the accompanying drawings. It is to beexpressly understood, however, that the drawings are not intended as adefinition of the invention but are for the purpose of illustrationonly.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings wherein like parts aremarked alike:

FIG. 1 is a side elevation of the preferred embodiment diagrammaticallyillustrating the principal features of the apparatus;

FIG. 2 is a plan view of the apparatus of FIG. 1;

FIGS. 3a-3f are diagrams illustrating the sequence of forming a finalstack of a predetermined number of blanks;

FIG. 4 is a cross-sectional view of the machine taken generally alongline IV-IV in FIG. 1 illustrating a blank squaring apparatus and aportion of a blank advancing mechanism;

FIG. 5a is a cross-sectional view of the machine taken generally alongline VV in FIG. 2 illustrating another portion of the blank advancingmechanism;

FIG. 5b is a cross-sectional view of the machine taken generally alongline VV in FIG. 2 illustrating another portion of the blank advancingmechanism;

FIG. 6 is a cross-sectional view of the machine taken generally alongline VIVI in FIG. 1 illustrating a gate mechanism for a first hopperportion of the machine;

FIG. 7 i a r -sectional view of the machine taken generally along lineVII-VII of FIG. 1 illustrating a portion of the blank advancingmechanism and a blankholddown device;

FIG. 8 is a cross-sectional view of the machine taken generally alongline VIIIVIII of FIG. 1 illustrating a lifting mechanism for lifting agroup of blanks in a second hopper and a discharge mechanism forremoving a stack of blanks from the second hopper;

FIG. 9 is a cross-sectional view of the machine taken generally alongline IX-IX of FIG. 1 illustrating a portion of the raising and dischargeportions of the machine;

FIG. 10 is an enlarged cross-sectional view of a portion of theadvancing mechanism appearing in FIG. b;

FIG. 11 is a side view of the advancing mechanism of FIG.

FIG. 12 is an enlarged side view of a portion of the lifting mechanismappearing in FIG. 1;

FIG. 13 is a cross-sectional view of the lifting mechanism of FIG. 12taken generally along line XIII-- XIII of FIG. 12;

FIG. 14 is a cross-sectional view of the lifting mechanism of FIG. 12taken generally along line XIV-XIV of FIG. 12;

FIG. 15 is a schematic illustrating the hopper level and conveyor clutchcontrols for the machine;

FIG. 16 is a schematic illustrating the motor control for the machine;and

FIG. 17 is a schematic illustrating the counter, final stack removal,and antijam controls for the machine.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred method of formingfinal stacks of a preselected number of blanks comprises the steps of,as illustrated in FIGS. 3a-3f, feeding or depositing individual blanks10 sequentially into a first hopper 12 to form a stack 14 of blanks 10therein (FIG. 3a); advancing a group 10a of a preselected number ofblanks 10, for example five blanks, into a second hopper 16 locateddownstream from the first hopper 12 (FIG. 3b); raising the group 10a inhopper 16 a sufficient distance to permit entry of another group 10b ofblanks 10, advancing from the first hopper 12, beneath the group 10athen in hopper 16 (FIG. 3c-3d); continuing the foregoing steps until afinal stack 10a-10b or more having the number of blanks l0 desired isformed in hopper 16; and thereafter removing the final stack 10a-l0 ormore from hopper 16 (FIG. 3e-3f).

A third group of blanks 10c may be advanced from hopper 12 to hopper 16while stack 10a-10b is being removed from hopper 16 (FIG. 3]).

Although FIG. 3d shows group 10a being lifted horizontally, preferablyonly the trailing edge 18 of group 10a is lifted or raised so that theleading edge 20 of group 1012 can be advanced beneath group 10a; thus,as group 10b continues to advance, it will completely support group 10awhen it moves completely beneath it. Thereafter, the trailing edge 18 ofstack 10a10b is raised to permit entry of the leading edge 20 ofsubsequent groups of blanks from hopper l2.

The apparatus for performing the foregoing method will hereinafter bereferred to as the stacker and is generally designated by numeral 30.The overall view of stacker 30 is diagrammatically illustrated in theside elevation of FIG. 1 and the top view of FIG. 2.

Referring now to FIGSJ and 2, stacker 30 generally includes a main framemember 32 formed as a rectangle; this frame may conveniently be madefrom steel channels joined at their ends by welding to form therectangle which generally defines the outer periphery of stacker 30. Apair of inner frame members 33 extend between the ends of frame 33inboard of the sides to form an inner rectangle having ends in commonwith frame 33 as best shown in FIG. 2.

Frame 33 supports a first conveyor generally designated 34 and a secondconveyor generally designated 36 located downstream from conveyor 34.The first conveyor 34 includes a head pulley shaft 38 and a tail pulleyshaft 40 (latter hidden from view in FIG. 2; see FIG. 4). Twocooperating pairs of chain sprockets 42 are mounted on each shaft 38 and40 in the positions indicated in FIGS. 2 and 4. A conveyor chain 44surrounds corresponding laterally aligned sprockets 42 between shafts 38and 40.

Conveyor 36 includes a head pulley shaft 46 and a tail pulley shaft 38,the latter shaft being common to both conveyors, that is, being the samehead pulley shaft 38 of conveyor 34. Three chain sprockets 48 aremounted on each shaft 46 and 38 in the positions indicated in FIGS. 2and 7. Note that the center sprocket 48 on shaft 38 is located betweenthe pairs of sprockets 42 and the other two sprockets 48 are locatedoutboard of sprockets 42.'A conveyor chain 50 surrounds correspondinglaterally aligned sprockets 48 between shafts 46 and 38.

As will be subsequently explained, both head pulley shafts 38 and 46 aredriven. Thus, sprockets 42 are keyed, or otherwise suitably secured, onshaft 38 in the conventional manner and are driven thereby; likewise,sprockets 48 are keyed to shaft 46 and are driven thereby. However,sprockets 48 on shaft 38 are secured to bearings 52 (FIG. 7) which arelocated on shaft 38; thus, sprockets48 can freely rotate around shaft38.

The first hopper 12 is defined on the bottom by the conveyor 34 and onits downstream or leading end by a gate assembly 54; on its upstream ortrailing end by a squaring assembly 56; and on its sides by a left sideguide 58L and a right side guide 58R (later shown in FIG. 1

The second hopper 16 is defined on the bottom by conveyor 36 and on itsdownstream or leading edge by a pivoting gate assembly 60; on itsupstream or trailing edge by a holddown assembly 62; and on its sides byright and left side guides 64L and 64R.

The stacker 30'is adapted for connection with a supply of blanks 10 fedsequentially into the first hopper 12. Such a supply is usually aconventional folder-gluer 66. (An example of a suitable folder-gluer isfound in Lopez U.S. Pat. No. 3,122,069). Foldergluer 66 usually includesa lower conveyor 68 from which folded blanks are ejected. It alsousually includes an upper conveyor 70 on top of the conveyor 68 forholding blanks 10 down against conveyor 68.

The stacker 30 includes a lower pull roll shaft 72 upon which aremounted a number of pull roll collars 74. An upper pull roll shaft 76 islocated above shaft 72; a pair of pull roll collars 78 are mounted onshaft 76. Both shafts 72 and 76 are mounted in bearings 79 secured inframes 80L and 80R, these frames being secured to the main frame 32.Thus, as blanks exit from the folder-gluer 66, they are engaged by thepull roll collars 74 and 78 which feed the blanks into hopper 12. Sincethe blanks 10 enter hopper 12 from above, they normally settle one at atime upon blanks lying on top of conveyor 34. However, to prevent anyinterferences between succeeding blanks, a conventional air blower 82can be used if desired to provide a jet of air on top of blanks 10 asthey enter hopper 12 to force such blank downward before a succeedingblank enters the hopper. Blower 83 can be mounted to a crossmember 84spanning the frames 80L and 80R and secured thereto.

The blanks 10 supplied by the folder-gluer 66 have been folded by thefolder-gluer; such that they enter hopper 12 as a collapsed tubularblank. The cross-section of a typical blank 10 entering hopper 12 isillustrated in FIG. 4. As can be seen in FIG. 4, blank 10 includes anouter flap 10F which overlaps an inner flap l0U. Adhesive has beenapplied between the overlapping flaps; this adhesive has not completelydried by the time the blank 10 enters hopper 12. It is also quite commonfor the blank to be folded out of square. Thus, one function of thestacker 30 is to square the blank before the adhesive dries.

The nature of the folded blank 10 permits it to be squared by pressingits leading and trailing edges between two rigid members. Thus, with theleading edges 20 of the blanks l0 lying against-the gate assembly 54, itis only necessary to press against the trailing edges 18 with a rigidmember to squeeze the blanks against the gate assembly 54 and therebysquare them.

The squaring assembly 56 for squaring the blanks 10 is illustrated bestin FIGS. 1 and 4. A squaring plate 86 is supported from a pair of rockershafts 88 by a pair of rocker arms 90. The rocker arms 90 are secured toplate 86 by welding or the like; the arms are free to pivot about rockershafts 88. Rocker shafts 88 are secured between the outer main frame 32and inner frame 33 as shown in FIG. 4. Thus, it can be seen that thesquaring plate 86 can be pivoted around rocker shafts 88 and by doing sowill urge the blanks 10 in hopper 12 against the gate assembly 54 whenpivoted forwardly thereby squaring the blanks.

Squaring plate 86 is pivoted or reciprocated backward and forward by acam assembly 94. Cam assembly 94 includes a cam shaft 96 extendingbetween the frames 80L and 80R; a pair of eccentric cams 98 are keyed tocam shaft 96 for rotation thereby. A link 100 surrounds each cam 98 andis connected to a bracket 102, such bracket being secured to squaringplate 86, by a pin 104 passing through both the link 100 and the bracket102 and secured thereto in a conventional manner. Thus, it can be seenthat as cam shaft 96 rotates, the cam 98 will cause the squaring plate86 to pivot backward and forward about rocker shafts 88. This, ofcourse, urges the blanks 10 against the gate assembly 54.

As shown in FIG. 4, the top edge 116 of squaring plate 86 is notched sothat it nests between the pull roll collars 74 when plate 86 is in itsbackward position.

The cam shaft 96 is mounted in bearings 106 secured to the frames 80 Land 80 R. A conventional chain sprocket 108 is secured to cam shaft 96and is driven by a chain 110 surrounding the sprocket 108 and anothersprocket 112. Sprocket 112 is mounted to a spline shaft 114. Splineshaft 114 is rotated by a drive means to be subsequently described.Thus, the rotation of spline shaft 114 drives the cam assembly 94 toreciprocate the squaring plate 86.

Again referring to FIG. 4, the tail pulley shaft 40 is mounted forrotation on bearings 118 secured to inner frame members 33. Thus, as thehead pulley 38 is driven, the chains 44 surrounding pulleys 42 on bothshafts 48 and 42 are rotated.

Between each pair of chains 44 are mounted a pair of advancing fingers120 spaced substantially equidistantly around the circumference of thechains. Advancing fingers 120 include upright portions 122. As bestshown in FIG. 1, finger 120 engages a group of blanks 10a, for example 5blanks, and advances them to hopper 16 on top of conveyor 36. Theremaining blanks 10 in hopper 12 fall on top of conveyor 34 as finger120 clears the gate assembly 54. The second finger 120 is thereafterbrought into engagement with the trailing edges 18 of blanks 10 inhopper 12 by the continuously rotating conveyor 34 to advance a secondgroup of blanks 10b in the same manner.

The second conveyor 36 includes a pair of sets oflifting fingers mountedto the center chain 50 and spaced substantially equidistant around thechain. Conveyor 36 is timed so that the group of blanks 10a enteringhopper 16 follow the lifting fingers 130 until the group is stopped bythe pivotable gate assembly 60. Thereafter, the second set of liftingfingers 130 approaches the group of blanks 10a, then in the secondhopper 16, from behind. The first finger 130a has a top slightly abovethe level of chains 50. Thus, it begins to lift the trailing edge 18 ofthe group 10a in hopper 16. Succeeding fingers 130b, c, and d are eachsucceedingly higher thereby raising the trailing edge 18 a sufficientamount to permit entry of another group of blanks 10b from the firsthopper 12 beneath the raised trailing edge 18 as illustrated in FIG. 1.As fingers 130 continue to advance, the group of blanks 10b entering thehopper l6 follow the fingers. As fingers 130 clear the pivotable gateassembly 60, the group of blanks 10a settles on top of the group 10b. Asthe next set of fingers 130 approaches the trailing edge 18, both groupsof blanks 10a and 10b are lifted to permit entry of a third group ofblanks 10c from hopper 12.

Thus, a final stack of blanks 10 is formed in hopper 16. When the stackattains a preselected number of blanks, the gate assembly 60 is pivotedcounterclockwise, as viewed in FIG. 1, to a horizontal position. Thispermits the stack to be removed from hopper 16 by the rotating chains 50upon which the stack is then resting. The stack is removed from hopper16 and moves to the final position 10F from which it may be passed on toanother conveyor, table or the like (not shown) for tying into afinished bundle.

Stacker 30 is made to accommodate blanks of different sizes. This isaccomplished by making the backstop assembly 54 moveable longitudinallytoward or away from the squaring assembly 56 to accommodate,eitherlonger or shorter blanks. The pivotable gate assembly 60 is similarlymoveable toward and away from the holddown assembly 62 for controllingthe space therebetween.

The side guides 58L and 58R are laterally moveable toward and away fromeach other to accommodate various width blanks in hopper 12. Likewise,side .guides 64L and 64R are moveable toward and away from each otherfor accommodating the widths of the blanks being handled in hopper 16.

Both the gate assembly 54 and pivotable backstop assembly 60 aresimultaneously moveable toward and away from the squaring assembly 56 sothat the longitudinal spacings of hoppers l2 and 16 are adjustedsimultaneously. This is accomplished by mounting the support members(for the gate assembly 54, pivotable backstop assembly 60, side guidesSSL and 58R, and side guides 64L and 64R) to a pair of subframes 140L,140R. The subframes 140 are supported above the main frame 32 bybrackets 142 secured thereto. Brackets 142 surround and are moveablealong a shaft 144 secured to each side of the main frame 32 by brackets146 as best illustrated in FIG. 6. Thus, it can be seen that as thesubframes 140 are moved toward and away from the squaring assembly 56,the longitudinal distance of hoppers l2 and 16 is automaticallyestablished. The supports for the gate assembly 54, backstop assembly60, and the supports for the side guides 58 and 64 will be subsequentlydescribed.

Subframes 140 are moveable longitudinally as best shown in FIG. 7. Anadjusting shaft 200 extends between subframes 140. A conventional spurtooth gear 202 is secured for rotation with shaft 200 just inside ofsubframes 140 (only one side is shown in FIG. 7, the other side beingsimilar). A spur tooth rack 204 is secured along the top inside edge ofthe sides of frame 32. A spur tooth pinion gear 206 is mounted forrotation about a stud 208 secured to the subframes; the pinion 206connects gear 202 with rack 204. A handwheel 210 is connected to the endof shaft 200 extending through subframe 140 L. Thus, as handwheel 210 isturned,it turns gears 202 and 206; gears 206 travel along racks 204thereby moving subframes 140 either toward or away from the squaringassembly 56. A conventional split shaft lock collar 211 surrounds shaft200 and is secured to subframe 140 L. A lever (not shown) passingthrough collar 211 is used to clamp the shaft 200 in the collar tomaintain subframe 140 in the position selected.

Thus, in viewing FIG. 1, it can beseen that frames 80 L, 80 R arestationary; the holddown assembly 62 is also stationary since it issecured to frame 32 in a manner to be described. The gate assembly 54and pivotable backstop assembly 60 are moveable longitudinally relativeto the stationary members just mentioned.

Since the conveyors 68 and 70 of the folder-gluer 66 are usuallylaterally moveable to accommodate various width blanks, it is desirablethat stacker 30 be made laterally moveable also. Accordingly, the mainframe 32 includes four wheel assemblies 150 secured thereto. Each wheelassembly 150 includes a bracket 152 secured to the bottom of frame 32and a wheel 154 journaled in the bracket 152. Preferably, the wheel 154is grooved to rest upon a mating rail 156 mounted to the floor. Thus, itcan be seen by referring to FIGS. 1 and 4 that the lateral position ofstacker 30 can be set where needed. If desired, the wheel assemblies 150can be motorized so that stacker 30 can be positioned automatically byan electrical control, such motor and controls not being shown as suchan arrangement can be easily provided.

The stacker 30 includes a final stack holddown assembly 160 for exertinga slight pressure on top of the final stack being formed in hopper 16 toprevent it from tilting from side to side. This holddown assemblyextends from the holddown assembly 62 to the downstream end of stacker30 so that it also prevents the stack being removed from hopper 16 fromtilting as it is being advanced on conveyor 36 to position 10F.

As previously mentioned, the blanks 10 enter hopper 12 as folded tubularblanks as best shown in FIG. 4. The overlap between the flaps 10F and10U are seldom in the center of the blank. Thus, it can be seen that astack 14 of such blanks will tend to lean because the stack will behigher on one side than the other because of the double thickness causedby the overlap.

For example, the top of a stack of five blanks to be advanced by fingers120 will likely be higher on one side. Thus, provision is made formaking the top, of the group to be advanced, level so that the advancingfingers 120 will advance the number of blanks desired. This isaccomplished by lifting the bottom of one side of the stack 14 withrespect to the other so that the top blank of the group to be advancedwill be level.

The bottom of the group is varied by lifting one side of the stackrelative to the other. FIG. 5a shows hopper rails 170. There is a railon each side of each chain guide channel 172 and still another rail 170further outboard near the inner frame member 33.

Rails 170 extend longitudinally along the bottom of hopper 12 from nearthe squaring plate 86, as seen in FIG. 2, to about the center of thehead shaft pulley 38; The rails 170 are pivoted at their trailing ends,as shown in FIG. 7, by a pin connection 174 between each rail and thechain guide channel 172; the outermost rails 170 are pivoted about asimilar pin connection 174 with the inner frames 33. Thus, the trailingends of rails 170 are substantially level and pivotable about pinconnections 174.

The leading ends of rails 170 each include a bracket 176 extendingbeneath the rails as shown in FIG. 5a. A crossbar 178 is looselyconnected to brackets 176 by pins 180. A threaded screw 182 is rotatablymounted to inner frames 33 by brackets 184. A threaded nut 186 issecured to outer rail 170 and surrounds screw 182. Thus, it can be seenthat rotation of screw 182 will raise or lower the outer rail 170. Asimilar arrangement is provided on the opposite side of the machine.Thus, the height of the outer rails 170 can be varied from near levelabout the trailing end pin connection 174 to the level desired near theleading end. Since the rails170 lying between the outer rails 170 arepinned to crossbar 178, their height is automatically adjustedsimultaneously with adjustment of the outer rails. Since the stack 14 ofblanks 10 in hopper l2 rests on these rails, it can be seen that the top(fifth) blank to be engaged by advancing fingers 120 can be made level.Note also that rails 170 support stack 14 above the chains 44 so thatthe groups'of blanks are not advanced by anything other than fingers120.

Threaded screw 182 on the right side of FIG. 5a is rotated by ahandwheel 190. This handwheel is connected to screw 182 by a connectingrod 192 which is supported on frame 32 by a bracket 194. A conventionalrightsangle gear box 196 is secured to the bottom bracket 184. Oneoutput shaft 197 of gear box 196 is connected in the ordinary manner toscrew 182 and the other output shaft 199 is similarly connected to rod192.

Thus, rotation of handwheel 190 rotates screw 182 in the directionnecessary to raise or lower rail 170 on the right side of FIG. a.

A similar bandwheel 190 is provided for raising or lowering rail 170 onthe opposite side of the machine. The arrangement of handwheels for bothsides is illustrated in FIG. 2.

The specific construction of the various assemblies previously generallydescribed can be more easily understood by reference to the Figuresshowing the stacker 30 at various sections along its length.

For example, FIG. 5b shows the support for chain guides 172 along theline VV' of FIG. 2. The trailing ends of chain guides 172, to besubsequently described in greater detail, rest on a cross-member 220extending between and secured to inner frames 33. A similar supportmember 222 is provided for supporting the leading ends of chain guides172 as shown in FIG. 2; this latter support also extends between and issecured to frames 33.

FIG. 6 shows, in addition to the mounting of subframes 140 as previouslydescribed, the gate assembly 54 and side guides 58.

Both the gate assembly 54 and side guides 58L, 58R are supported on across-member 230 extending between and secured to subframes 140. Asshown in FIG. 1, cross-member 230 is conveniently made from two barswith a space between them. A side guide holder 232, shaped as a T incross-section, rests between the bars 230. A bracket 234 is secured toeach side guide 58L, 58R and extends beneath support 230. A screw 236passes through holder 232 and is threadedly secured in bracket 234.Thus, by loosening screw 236 slightly, either side guide 58L, 58R may bepositioned along support 230 to accommodate the width of blanks 10 beinghandled by stacker 30. When the side guides are positioned as desired,screw 236 is tightened thereby clamping holder 232 to support 230 whichlocks the side guides 58 in position. If desired, a handwheel (notshown) can be attached to screw 236 for easier operation of the screw236.

Each side guide 58 includes a face portion 240 against which the leadingedges of the stack 14 of blanks 10 are urged by squaring assembly 56.Each side guide 58 also includes a side plate 242 for laterallyrestraining the blanks. Preferably, the side plates 242 extenddownwardly to beneath the level of the bottom of the stack 14established by rails 170.

Gate assembly 54 also includes a similar bracket 233 clamped to supportbars 230. A pair of gate side -plates 244 are suspended from bracket 233by a threaded stud 246 and cross-plate 248. A short pulley shaft 250 ismounted for rotation between plates 244. The adjusting shaft 200,previously mentioned, passes. through the lower part of side plates 244.A pulley 252is secured for rotation with pulley shaft 250; a similarpulley 254 is bearing mounted for rotation about adjusting shaft 200. Aconventional woven or rubber belt 256 surrounds pulleys 252 and 254; asmall gear motor 258 is mounted to one of the side plates 244 and has anoutput shaft (not shown) connected to pulley shaft 250 in a conventionalmanner; motor 258 thereby rotates belt 256 at a slow speed.

The upstream face of belt 256 lies substantially on the same plane asthe face 240 of side guides 58 (see FIG. 1). Thus, as the blanks 10 restagainst the gate assembly 54, belt 256 urges the leading edges 20downward against conveyor 34 by friction between the belt and theblanks.

Stud 246 is threaded through cross-plate 248 so that the side plates 244can be raised or lowered by a handwheel 260 secured to stud 246. Thispermits the bottom of plates 244 to be raised or lowered to let athinner or thicker group of blanks to pass beneath them. Thus, the blanklying above the group being advanced is not permitted to pass beneaththe gate assembly 54. I

FIG. 7 shows, in addition to pulley shaft 38 and its associatedsprockets and the subframe adjustment arrangement previously described,the holddown assembly 62 which is generally located between hopper l2and hopper 16 to provide an intermediate holddown for the groups ofadvancing blanks.

Holddown assembly 62 essentially comprises a spring steel band 270, suchas a band sold under the tradename Negator sold by Hunter Spring,Hatfield, Pa. as illustrated in their Bulletin 310-67, extending from aposition above pulley shaft 38 to the underside of gate assembly 54 (seeFIG. 1). The purpose of band 270 is to prevent a group of blanks 10being advanced from hopper 12 to hopper 16 from springing up before theypass beneath the trailing edges 18 of the stack of blanks 10 in hopper16. The group of blanks being advanced may be initially compressedslightly by the weight of the stack in hopper 12. If the blanks arepermitted to spring up, they may jam into the back of the stack inhopper 16. By keeping the group compressed, it will always enter thespace provided by the lifting of the stack in hopper 16.

Since the supports for holddown-assembly 62 must remain longitudinallyfixed, a pair of vertical support bars 272 are secured to frame 32 withthe right hand bar being shown secured to frame 32 on the left side ofFIG. 7 (the other bar being similarly secured but omitted to show otherparts). A cross-brace 274 rigidly spaces the tops of supports 272. Across rod 276 is also secured between bars 272 beneath the cross-brace274. The band 270 is coiled around crossrod 276 and extends downward andaround another cross-member 278 secured between support bars 272; theband continues forward to where it is secured to the bottom ofside'plates 244 of the gate assembly 54.

Band 270 is constructed to have an inherent tendency to coil around rod276. Thus, when subframes 140 are moved toward the squaring assembly 56,the gate assembly 54 moves forward also thereby uncoiling band 270; whengate assembly 54 moves toward the holddown assembly 62, the band 270automatically coils around rod 276. In this manner, a portion of theband 270 always lies across the top of the group of blanks beingadvanced from hopper 12 to hopper 16.

FIG. 8 shows the construction of the pivotable gate assembly 60. A pivotshaft 280 is mounted in bearings 282. Since shaft 280 must movelongitudinally with subframes 140, the bearing 282 on the right side ofFIG. 8 is secured to bracket 284 which is secured to subframe 140L. Theother bearing 282 is secured to an auxiliary bracket 286 secured tosubframe 140R by supports 288 outboard of the main frame 32.Longitudinal slots 290 are provided in frames 32 and 33; thus, assubframes 140 are moved longitudinally, pivot shaft 280 moves with them.

A pair of pivot arms 292 are secured to shaft 280 laterally between thechains 50 as shown in FIG. 8. These arms provide a stop against whichthe leading edges of the blanks in hopper 16 are restrained from forwardmovement during the time that a stack is being formed in hopper 16.

When the stack of blanks 10 in hopper l6 attains the number desired, thepivot arms 292 are pivoted to a horizontal position such as indicated byarrow 295 in FIG. 1. This removes the restraint against forward travelof the stack which rests on conveyor 36 and the stack then moves toposition 10F for removal from stacker 30. When the stack is removed,arms 292 are pivoted to their upright position.

Pivoting of shaft 280 is accomplished by air cylinder 300. Cylinder 300includes a conventional clevis mounting 302 attached to portion 304 ofbracket 286 by a pin 306 in the usual manner. Actuating rod 301 ofcylinder 300 also includes a clevis mounting 308 attached to anactuating arm 310 by a pin 312. Arm 310 is secured to shaft 380; thus,when actuating rod 301 is extended by air pressure in cylinder 300, itpivots arm 310 thereby pivoting shaft 280 and pivot arms 292.Conversely, a spring, or air pressure applied in the opposite directionwithin the cylinder, returns arms 292 to their upright position.

FIG. 9 shows the head pulley shaft 46 of conveyor assembly 36. Shaft 46is mounted in bearings 320 which are secured to inner frame 33. Chainsprockets 48 are secured for rotation with shaft 46. Another chain drivesprocket is secured to the end of shaft 46 to drive it as will besubsequently explained.

FIGS. 10 and 11 show the construction of the advancing fingers 120 onconveyor 34 in greater detail. FIG. 10 is an enlarged view of thecross-section of the conveyor shown in FIG. 5b. The chain guide 172 issupported above cross-member 220 by a bracket 330 and between rails 170.Chain guide 172 is secured to bracket 330 by screws and nuts 332 and334; bracket 330 may be welded to cross-member 220 or bolted thereto(not shown). Chains 44 are laterally spaced as shown. Chains 44 includespecial outside links 336 which extend above the chain as shown in FIG.11. A stud 338 passes through the special links 336 midway between theconventional chain rollers 340. Stud 338 includes three rollers 342; thecenter roller 342 travels along roll support 334 secured to the bottomof the chain guide 172. The outer rollers 342 travel beneath flanges 346on the chain guide 172. Thus, the chains 44 are supported horizontallyso that the advancing finger 120 cannot tilt.

The advancing finger 120 includes two side plates 350 through which stud338 passes to connect them to the chains. Washers 352 space the rollers342, the chains 44, and the side plates 350 the desired distance asshown. Nuts 354 are threaded on the ends of stud 338 to retain thevarious parts thereon.

Another single roller 342 is mounted between side plates 350 at thetrailing end of the side plates in a manner similar to that previouslydescribed. The trailing roller 342 rides on roll support 344 to maintainthe advancing finger in an upright position when it is on the top flightof the chain but permits the trailing end of the fingers 120 to dropaway whentraveling on the bottom flight of the chain. This permitsunrestricted travel of the fingers 120 around the sprockets 42.

Side plates 350 are joined by a cross-plate 360 to make the finger 120rigid and to support upstanding portion 122 which is secured thereto bya flat head screw 362. FIG. 1 shows two fingers 120 spaced substantiallyequidistant around the circumference of chains 44. Thus, two groups ofblanks are removed from the stack 14 in hopper 12 for each revolution ofthe chains 44 around the pulley shafts 38 and 40. FIGS. 12, 13 and 14illustrate the lifting fingers in greater detail. FIG. 13 is an enlargedview of the lifting fingers shown in FIG. 8.

Chains 50 are conventional roller chains except that they includespecially formed outer links 370 which extend above the normal chainlinks. Links 370 support finger posts 372a, b, c and d. Posts 372 arelocated between the links 370; a pair of screws 374 pass through thelinks 370 and through the posts 372 with nuts 376 securing the assemblytogether.

The top of each post 372 includes a stud 378 on the ends of which arerollers 380 (e.g., conventional ball;

bearings) retained by nuts 382 threaded on the ends of stud 378. Thestud 378 is retained in the post 372 by a set screw 384.

Rollers 50R of chain 50 are supported by guide bar 390. Guide bar 390 issupported by brackets 394 above two cross-members 392 extending betweenthe frames 33. Both cross-members 392 appear in the top view of thestacker 30 in FIG. 2.

A pair of support rails 396 are also supported by brackets 398 above thecross-members 392.with one rail being on each side of guide bar 390(left support rail is omitted from FIG. 13). Support rollers 400 aremounted on rails 396 by studs 402 and nuts 404. Rollers 400 support thestack of blanks 10 in hopper 16; when pivot arms 292 are moved to ahorizontal position, the stack moves across rollers 400.

Chains 50 also include specially formed outer links 410 upon whichadvancing blocks 412 are mounted by screws 414 threaded into links 410.Blocks 412 can be metalic but are preferably made of wood as shown.

The outboard chains 50 have blocks 412 around their entire periphery;the center chain 50 has blocks 412 between the lifting fingers 130. Thetop of blocks 412 are about the same height as the top of support roller500. Thus, the stack of blanks 10 in hopper l6 rests on rollers 400 andblocks 412.

As shown in FIG. 12, posts 372 are each succeedingly higher than thenext; thus, as the fingers 130 i move in the direction of arrow 420, thelowest roller 380 rolls beneath the trailing edge 18 of the stack inhopper l6 and lifts the stack slightly off blocks 412 which are slidingbeneath the stack since the stack is restrained against forward travelby pivot arms 292. As fingers 130 advance, the next roller 380 lifts thestack a little higher until the stack finally rests on top of thehighest roller 380 on post 372d. At this time, another group of blanksadvancing from hopper 12 enters hopper 16 in the space, created bylifting fingers 130, between the bottom of the stack and the top ofblocks 412. The group from hopper 12 continues to advance beneath thestack because it is being pushed by advancing fingers 120. When theadvancing group reaches pivot arms 192, it is restrained but the liftingfingers 130 continue beyond the pivot arms 292.

Hopper 16 is proportioned so that advancing fingers 120 clear the stackin hopper 16 and continue around the sprocket 42 and back toward thefront of the machine along the lower flight of chains 44. As the liftingfingers 130 clear the pivot arms 292, the stack in hopper 16 rests onthe group just advanced from hopper 12. In this manner, a stack ofblanks is continuously formed in hopper 16. When the stack attains aselected member of blanks (in multiples of'the number of blanks fed fromhopper 12), the pivot arms 292 are moved to the horizontal position.Then, friction between blocks 412 and the bottom of the stack causes thestack to advance and thereby be removed from hopper 16 across rollers400.

As stack is removed from hopper 16, the holddown assembly 160 preventsthe stack from tilting over. Assembly 160 includes a conventionalrollerskate conveyor (see FIG. 1) which consists primarily of a supportbar 440 with roller bearing wheels 442 secured on both sides thereof asshown in FIG. 9.

Assembly 160 is supported on its upstream end by a bracket 444 mountedto crossbar 274 from which a chain or wire 446 is suspended; chain 446is attached to the end of support bar 440. This flexible connectionpermits the assembly to rest on top of the stack being formed in hopper16 and to rise with it as the stack is lifted by fingers 130.

The downstream end of assembly 160 is pivotally connected to an arm 4,50mounted in one corner of frame 32 (see FIG. 2) and which hangs acrossthe stacker 30 to its lateral center. A support rod 452 is connected toarm 450 and pivotally to bar 440. Rod 452 is preferably verticallyadjustable so that the assembly can be located at the height needed forthe stack being handled.

Stacker 30 can be independently driven by its own motor but ispreferably driven from folder-gluer 66. Basically, this is accomplishedby connecting stacker 30 to a gear box 500 which is driven by a lineshaft 502 from folder-gluer 66.

As will be explained in greater detail, gear box 500 drives the squaringassembly 56, the pull rolls 72 and 76, head pulley shaft 38, and headpulley shaft 46.

The squaring assembly 56 is driven by spline shaft 114 extending fromgear box 500 and supported on frame 32 by bracket 504. A roller chainsprocket I12 mounted on spline shaft 114 is connected to spline 108 oncam shaft 96 by a conventional roller chain 110 surrounding thesprockets. Shaft 114 is splined or keyed so that sprocket 112,restrained against lateral movement by bracket 504 (see FIG. 2), canslide along shaft 114 when stacker 30 is laterally positioned aspreviously described. The squaring plate 86 reciprocates about rockershafts 88 as previously described when cam shaft 96 is driven.

As shown in FIG. 4, cam shaft 96 extends through bearing 106 in frame80R. A conventional spur tooth gear 506 is mounted on the end of camshaft 96 for rotation therewith. The lower pull roll shaft 72 extendsthrough bearing 79 in frame R. A spur tooth gear 508 is mounted on theend of shaft 72 for rotation therewith. Spur tooth pinion gear 510 isbearing mounted on a stud 512 secured to frame 80R and is positioned toconnect gear 508 with gear 506 for rotation thereby which rotates pullroll shaft 72. Another spur tooth gear 514 is secured for rotation withthe end of upper pull roll shaft 76 extending through bearing 79 inframe 80R. Gear 514, 'and consequently shaft 76, are driven by gear 508.The sizes of the gears are selected in the known manner to provide thedesired rotational speed for the pullrolls and squaring assembly.

A chain sprocket 516 is also mounted to the end of cam shaft 96 adjacentgear 506 (FIG. 4). As best illustrated in FIG. 2, sprocket 516 isconnected by a roller chain 518 to another sprocket 520. Sprocket 520 ismounted for rotation with the end of a short shaft 522 bearing mountedin frames 32 and 33. Shaft 522 passes through and is connected to theinput hub (not visible) of a clutch 524, the purpose of which will besubsequently explained. A spur tooth gear 526 also surrounds shaft 522but is connected for rotation with the output of clutch 524 and not forrotation by shaft 522.

Although an electric clutch can be used, clutch 524 is preferably airoperated. A satisfactory type is sold under the Tradename Maxitorq madeby Carlyle Johnson Machine Company, Manchester, Connecticut such asSeries AH illustrated in their Bulletin No. 101.

. Another short shaft 530 is bearing mounted in frames 32 and 33adjacent shaft 522. A spur gear 532 is mounted for rotation with shaft530 and in mesh with gear 526 so as to be driven thereby. A conventionalV- belt pulley 534 is mounted for rotation with the end of shaft 530outboard of frame 32.

The end of head pulley shaft 38 extends beyond frame 32 as shown in bothFIGS. 2 and 7 and is supported in a bearing 537 in an auxiliary supportbracket 539 secured to frame 32. A differential 536 is mounted on theend of shaft 38. The differential 536 is preferably one sold under theTradename Rotomission made by Airborne Accessories Corporation,Hillside, New Jersey, such as illustrated in their Bulletin lR62.

The differential 536 includes an integral input pulley 538 formed in itsperiphery which is driven by a V-belt S39 surrounding it and pulley 534.The differential functions such that its output hub (not visible)surrounds shaft 38 and drives the shaft.

However, the speed of shaft 38 can be changed from the input speed ofthe differential 536 in the following manner. The differential 536includes an auxiliary input hub (not visible) axially adjacent itsoutput hub. To this hub is secured a chain sprocket 540. An electriccorrection motor 542 is mounted on bracket 539 and includes output shaft544 upon which is mounted a sprocket 546; a chain 548 connects sprocket546 to sprocket 540.

Motor 542 is by-directional. Thus, operation of this motor adds to orsubtracts from the speed of pulley shaft 38 through the differential 536for reasons to be later explained.

The opposite end of shaft 38 has another air clutch 550 mounted thereonsimilar to clutch 524. A sprocket 552 is connected to the output ofclutch 550. Head pulley shaft 46 of conveyor 36 includes a sprocket 554mounted thereon as shown in FIGS. 2 and 9. A chain 556 connects sprocket$52 to sprocket 554 for driving shaft 56.

Both clutches 524 and 550 are constructed so that a supply of air underpressure engages them; when engaged, they provide an output rotating atthe same speed as the input. When the air supply is removed, no outputis supplied. Thus, referring to FIG. 2, it can be seen that as clutch524 is disengaged, the pull rolls 74 and 76 and squaring assembly 56will continue to operate but neither head pulley shaft 38 nor 46 willrotate. This arrangement permits a stack 14 of blanks 10 to be formed inhopper 12 before the conveyors 34 and 36 are driven by supplying air toclutches 524 and 550.

Clutch 550 can be independently disengaged. This permits second conveyor36 to remain stationary while first conveyor 34 is jogged to placeadvancing fingers 120 in a different lineal position with respect tolifting fingers 130. This is usually necessary since changing the lengthof hoppers l2 and 16 to accommodate blanks of another length affects thetiming between the two conveyors, it being obvious that a group beingadvanced from hopper 12 preferably enters hopper 16 immediately behindthe lifting fingers 130.

Since the final number of blanks in the stack in hopper 16 can bepreselected in increments of the number of blanks in the groups advancedfrom hopper 12, it can be seen that, if a greater number of blanks isdesired in hopper 16, the stack in hopper 16 must remain for a longertime. Thus, the stack 14 of blanks being formed in hopper 12 can get toohigh. Conversely, if a smaller number of blanks is desired in hopper 16,the stack in hopper 12 can get too low. A suitable stack height control(to be subsequently explained) is provided for energizing correctionmotor 542. If there are too many blanks in hopper 12, motor 542 adds tothe speed of pulley shaft 38; this speeds up both conveyors 34 and 36.Thus, the blanks are stacked more quickly thereby reducing the height ofthe stack 14 in hopper 12.

Conversely, if the stack in hopper 12 gets too low, motor 542 is run inthe opposite direction to slow down conveyors 34 and 36 so that thestack in hopper l2 builds up to the desired height.

CONTROL AND OPERATION The control system for stacker 30 provides thesensing and control of the mechanical functions of the stacker. Thus, itmonitors the operating state of the stacker and provides controlinformation to the mechanical actuators of the system in a predeterminedmanner to cause the system to react to various conditions in the propermanner.

The control system can be divided into two main functions, the firsthopper control (hopper l2) and the second hopper control (hopper 16).

The first hopper control functions to interface the entire stacker 30with folder-gluer 66 to maintain a stack 14 of blanks 10 in hopper 12from which the final stacks are formed in hopper 16. The first controlconsists of hopper level and conveyor clutch controls.

Referring to FIG. 1, blanks 10 enter the machine from folder-gluer 66 ina continuous stream of blanks. As the blanks 10 enter the stacker 30,they are directed such that they fall in a pile or stack 14 in hopper12. From the bottom of this stack, smaller stacks or groups of 5 blanksare removed consecutively by the advancing fingers 120 running underhopper 12. Since conveyor 34 is synchronized with folder-gluer 66, thetotal number of blanks removed from hopper 12 is approximately the sameas the number supplied to hopper 12. Although blanks in groups of 5 arepreferably removed from hopper 12,.the machine can be proportioned forremoval of any number desired.

Due to a slight difference in the speeds of conveyor 34 and thefolder-gluer 66, and to unusual conditions (unusual in the sense thatthey do not occur during normal running circumstances) occurring duringthe start and end of a run, or during a run when the blanks supply maybe interrupted for some reason, it is necessary to provide a means foradjusting or stopping the motion of conveyor 34.

Such speed adjustment is mechanically accomplished by differential 536which can change its output to input shaft speed relationship by a fixedpercentage both above and below the input shaft speed. The adjustmentinput to differential 536 is provided by a small correction motor 542which is controlled by the first hopper control. Since differential 536forms the drive interface between conveyor 34 and the line shaft 502from the folder-gluer 66, the relative speed of conveyor 34 andfolder-gluer 66 can be changed at will. This means the amount of blanksor stack height in hopper 12 can be controlled.

Stopping action for conveyor 34 is provided by clutch 524 which couplesline shaft 502 with conveyor drive shaft 530 which in turn drivesconveyor 34 through differential 536: Clutch 524 is also controlled bythe first hopper control during starting and stopping of the run and forcertain adjustment procedures during machine set up.

FIG. 15 shows the first hopper control which includes level controlcircuitry for controlling the height of the stack in hopper l2 and forcontrolling clutch 524. Circuitry for controlling correction motor 542(which drives differential 536) and its reversing magnetic motor starteris shown in FIG. 16; motor 542 includes a brake for automaticallylocking motor output shaft 544 when the motor is not energized.

The level control circuitry consists partially of three photo-electriclimit switches labeled 600, 602, and 604. The light sources andphotocells for all three are located in a common assembly 606 which ismounted on frame R (shown diagrammatically in FIGS-1 and 2). They arepositioned such that their light beams are directed across the machineperpendicular to the direction of blank flow and parallel to the floor.Located opposite each light source is a reflector 608 (FIG. 2) whichdirects the light beam back to the appropriate photocell. All threephotoelectric limit switches 600, 602, and 604 are dark operated whichmeans their contacts change state when the light beams to the reflectors608 are broken. The configuration shown in FIG. 15 is for lightedconditions i.e., the light beams between the reflectors and photocellsare unbroken. Built into 600 and 602 are adjustable time delays on darkoperation to allow blanks to fall through their beams without causingoperation of these limit switches.

Associated with switches 600, 602 and 604 are a control relay 610, motorstarter control 612, and MANUAL-AUTO selector switch 614, which form thebalance of the level control. Also included are a set of contactslabeled 616 (located in the main drive cabinet for folder-gluer 66 notshown) which close whenever the drive motor for folder-gluer 66 isrunning.

The control for clutch 524 consists of a main clutch solenoid 618,auxiliary clutch-brake solenoid 620, contacts of control relay 622,proximity switch 624 and selector pushbuttons 614 and 628 labeled OPERA-TION MODE and MANUAL DRIVE.

The second hopper control (for hopper 16) consists of counter, stackremoval and anitjam controls circuitry as shown in FIG. 17. The purposeof the second hopper control is basically to count groups of blankscoming from the conveyor 34 and to signal the gate assembly 60 to ejector remove the newly formed stack when a preselected number of blanks arepresent in the final stack in hopper 16. In addition, various safeguardsare built into the circuitry to prevent accidents and automatically stopthe machine when a jam occurs.

The counter circuit consists of counter 640 with associated limit switch642 and selector switch 614. Counter 640 is of the preset type wherebyclosure of switch 642 causes the count to advance from zero in steps offive (five blanks at a time are delivered to hopper 16 to the presetnumber selected). Upon coincidence of the counter and preset numbers, asignal emerges on line 646 from the S terminal to relay 648 of the stackremoval control. Simultaneously, the counter number is reset to zero bystepping relay 650 through terminals H, F, and J of the counter. Thisoperating cycle repeats for each final stack formed by stacker 30.Selector switch 614 also provides a reset signal to the counter 640whenever 614 is placed in the MANUAL" position.

Limit switch 642 is preferably of the standard industrial spring wireactuated type although it can be any type of switching device which hasthe capability of providing a contact closure output coincident with thepassing of the five-blank group of blanks from the conveyor 34 to thehopper 16.

The stack removal control functions to allow the gate assembly 60 toremain closed while the final stack is forming in hopper 16 and openwhen the preselected number of blanks is attained. The control consistsof control relay 648, stepping relay 650, photoelectric limit switch652, gate solenoid 654, and selector switch 614.

The gate assembly 60 remains closed or upright as long as gate solenoid654 is electrically energized through contacts 622 and 648. With theselector switch 614 in the AUTOMATIC position, the counter 640 willtotalize the number of five-blank groups accumulated in hopper l6. Whenthe preselected count is attained, the counter 640 energizes relay 648.The normally-closed contacts of 648 in lines 660 and 662 will open,de-energizing 654. Thus, the gate assembly 60 will open (pivot tohorizontal) which allows the completed stack to start moving past thegate.

Photoelectric limit switch 652 is positioned over the gate assembly 60in such a way that its reflector 653 will not be in the beam until thegate arms 292 open since the reflector 653 is mounted on the end of onegate (see FIGS. 1 and 2). As the gate arms 292 open, the light source of652 is energized by normally-open contacts of 648 in line 664. As thegates 292 reach the fully open position, light will be reflected fromthe gatemounted reflector 653, causing the contacts of 652 to close,energizing stepping relay 650.

Stepping relay 650 is preferably a cam-operated stepping switch whichexperiences a change in the state of its contacts upon a momentaryenergization of its coil. As soon as the stack moving through the gateassembly 60 area covers the gate reflector 653, the beam from 652 isbroken, deenergizing 650. The contacts of 650 will remain closed at thistime.

The contacts of 650 in lines 666, 668 and 670 will reset counter 640 tozero. In addition, another set of contacts of 650 will close,maintaining current to the coil of 648, thereby holding the gate arms292 open or horizontal.

As soon as the stack clears the gate 292, the beam from 652 will againimpinge upon the reflector 653 causing the contacts of 652 to close andstepping relay 650 contacts to open. This allows the gate arms 292 toclose and the counter 640 to start counting 5-blank groups for formingthe next stack in hopper 16. Thus, the cycle is repeated.

When OPERATING MODE" selector 614 is set to the MANUAL" position, 648 isenergized, opening the gates 292. This is recommended whenever anoperator needs to manually adjust the machine to prevent injury from thegates 292 suddenly closing automatically.

An antijam control circuit is provided to automatically stop the mainfolder-gluer drive whenever a blank jam occurs in the gate assembly 60area. In addition, it requires manual resetting before the machine canbe restarted. The antijam control consists of proximity switch 680,control relay 622 and lighted RESET pushbutton 684. In addition, anoperator alarm can be provided if desired to signal a jam condition.

Proximity switch 680 is located such that conveyor 36 will trigger itwhen the conveyor is in a particular position. This position isdetermined by the physical set-up of the stacker 30 such thatcoincidence with the gate arms 292 in an open or horizontal positionindicates the stack is not in proper position. The stack being out ofposition will cause a jam if the condition is allowed to exist longenough for another five-blank group to enter the gate assembly 60 area.When the gates 292 are open, the contacts of 648 in lines 664 and 682will be closed, causing current to flow through the contacts of 680 tothe coil of relay 622. Thus, a jam condition energizes 622 which latchesthrough RESET pushbutton 684'and its own normally open contacts. Anotherset of normally-closed contacts of 622 are connected in lines 686 and688 to provide a stop signal to the main drive of folder-gluer 66. Thedrive cannot be restarted until the contacts of 622 are again closed.

In the event of a jam, the operator is required to set 614 to theMANUAL" position to ensure his safety. This must be done or the controlwill not reset. After

1. A method of forming a final stack of blanks of preselected numbercomprising the steps of: depositing individual blanks sequentially intoa first hopper thereby forming a first stack of such blanks therein;advancing a second stack of blanks of preselected number from the bottomof said first stack into a second hopper downstream from said firsthopper; raising said second stack of blanks in said second hopper asufficient distance to permit entry of a consecutive second stack ofblanks advancing from said first hopper beneath the second stack ofblanks then in said second hopper; continuing the foregoing steps untilsaid final stack of blanks of preselected number is formed in saidsecond hopper; and thereafter removing said final stack of blanks ofpreselected number from said second hopper.
 2. The method of claim 1further including the steps of counting the number of said second stacksof blanks advancing from said first hopper and removing said final stackwhen it contains a preselected number of said second stacks.
 3. Themethod of claim 1 further including the step of squaring said firststack of blanks in said first hopper.
 4. The method of claim 1 whereinraising said second stack of blanks in said second hopper compriseslifting the trailing edge of said second stack.
 5. The method of claim 1further including the step of holding down said final stack during theformation thereof.
 6. The method of claim 1 further including the stepof holding down said second stacks of blanks advancing from said firsthopper.
 7. The method of claim 1 further including the step ofmaintaining the height of said first stack in said first hopper withinpredetermined limits.
 8. The method of claim 1 further including thestep of stopping the formation of said final stack automatically inresponse to a jam in said second hopper.
 9. A method of forming a finalstack of blanks of preselected number comprising the steps of: feedingindividual blanks sequentially onto a first conveyor; intercepting theflow of said blanks along said first conveyor for forming a first stackof blanks thereon; periodically advancing a second stack of blanks fromthe bottom of said first stack to a second conveyor downstream from saidfirst conveyor; intercepting the advancement of said second stack alongsaid second conveyor; lifting the trailing edge of said second stack onsaid second conveyor to define a space between said second stack andsaid second conveyor; advancing another said second stack of blanks fromsaid first stack into said space for forming said final stack of blankson said second conveyor consisting of said second stacks; and thereafterremoving said final stack from said second conveyor.
 10. The method ofclaim 9 further including the steps of counting the number of saidsecond stacks formed on said second conveyor and discharging said finalstack therefrom when it contains a preselected number of said blanks.11. The method of claim 9 wherein periodically advancing a second stackof blanks comprises periodically advancing a second stack consisting offive blanks from the bottom of said first stack.
 12. Apparatus forforming a final stack of blanks of preselected number, comprising: afirst hopper means for receiving individual blanks sequentiallydeposited therein for forming a first stack of such blanks; advancingmeans for advancing a second stack of said blanks from the bottom ofsaid first stack into a second hopper means downstream from said firsthopper means; lifting means for raising said second stack of blanks insaid second hopper means a sufficient distance to permit entry of aconsecutive second stack of blanks advancing from said first hoppermeans beneath the second stack of blanks in said second hopper means toform said final stack; and discharge means for removing said final stackfrom said second hopper means, said discharge means being operable inresponse to said final stack attaining a preselected number of saidsecond stacks of blanks consecutively entering said second hopper means.13. The apparatus of claim 12 further including squaring means forsquaring said blanks in said first hopper means.
 14. The apparatus ofclaim 12 further including counting means for counting the number ofsaid second stacks of blanks advancing into said second hopper means,said discharge means operative in response to said counting meansattaining a preselected number corresponding to the number of blanks insaid final stack.
 15. The apparatus of claim 12 wherein said liftingmeans is operative for lifting the trailing edge of said second stack ofblanks in said second hopper.
 16. The apparatus of claim 12 furtherincluding holddown means for holding down said final stack during theformation thereof.
 17. The apparatus of claim 12 further includingintermediate holddown means for holding down consecutive ones of saidsecond stacks of blanks advancing to said second hopper means from saidfirst hopper means.
 18. The apparatus of claim 12 further includingheight control means for maintaining the height of said first stack insaid first hopper means within predetermined limits.
 19. The apparatusof claim 12 further including antijam means operative in response to ajam of said second stacks of blanks in said second hopper means forautomatically stopping the formation of said final stack.
 20. Theapparatus of claim 12 wherein said first hopper means comprises: firstconveyor means for supporting said first stack of said blanks; gatemeans adjacent the leading edge of said first stack; squaring meansadjacent the trailing edge of said first stack for urging the blanks insaid hopper against said gate means for squaring said blanks; and firstside guide means adjacent the sides of said first stack for maintainInglateral alignment thereof.
 21. The apparatus of claim 20 wherein saidadvancing means comprises: at least one advancing finger means attachedto said first conveyor means and having an upright portion engageablewith the trailing edge of a selected number of said blanks in said firststack for forming said second stacks of blanks during advancement ofsaid finger means beneath said first stack in said first hopper means.22. The apparatus of claim 12 wherein said second hopper meanscomprises: second conveyor means for supporting said final stack; saiddischarge means including a pivotable gate means for intercepting theflow of said second stacks of blanks along said second conveyor means;first holddown means adjacent the trailing edge of said final stack forholding down the uppermost one of said second stacks of blanks advancingfrom said first hopper means; and second side guide means adjacent thesides of said final stack for maintaining lateral alignment thereof. 23.The apparatus of claim 22 wherein said lifting means comprises: at leastone lifting finger means attached to said second conveyor means andhaving a surface for lifting the trailing edge of the lowest of saidsecond stack of blanks in said final stack to a height greater than theheight of a second stack of blanks advancing from said first hoppermeans to permit entry thereof beneath said final stack, said surfacebeing inclined from the trailing edge of said final stack upwardlytoward said first hopper means for gradually lifting said lowest secondstack of blanks.
 24. The apparatus of claim 12 wherein said dischargemeans comprises: a second conveyor means for supporting said finalstack; pivotable gate means for intercepting the flow of said secondstacks of blanks advancing into said second hopper means; and controlmeans operable in response to said final stack attaining a preselectednumber of blanks for pivoting said pivotable gate means to asubstantially horizontal position, whereby said second conveyor meansremoves said final stack from said second hopper means.
 25. Theapparatus of claim 13 wherein said squaring means comprises: a pivotablesquaring plate means adjacent the trailing edge of said first stack forurging the blanks in said first hopper means against a gate meansadjacent the leading edge of said first stack; and drive means forreciprocally pivoting said squaring plate means against said trailingedge.
 26. The apparatus of claim 14 wherein said counting meanscomprises: an electrical limit switch means located along the path ofadvance of said second stacks of blanks from said first hopper means tosaid second hopper means operable in response to the advance of saidsecond stacks of blanks along said path for supplying a signal to saiddischarge means corresponding to the number of said second stackspassing said switch means for operating said discharge means when apreselected number of said second stacks have been counted.
 27. Theapparatus of claim 16 wherein said holddown means comprises: a thirdconveyor means extending along the top of said second hopper means forexerting a vertically yielding holddown pressure against the top of saidfinal stack during the formation thereof to prevent tilting of saidfinal stack.
 28. The apparatus of claim 17 wherein said intermediateholddown means comprises: a flexible band means extending along the pathof advance of said second stacks of blanks between said first hoppermeans and said second hopper means for maintaining the height of saidsecond stacks of blanks during advancement thereof from said firsthopper means to said second hopper means.
 29. The apparatus of claim 18wherein said height control means comprises: a first light sensitivecontrol means for sensing the top of said first stack in said firsthopper means at a maximum desired height; and a second light sensitivecontrol means for sensing the toP of said first stack in said firsthopper means at a minimum desired height, said first control meansoperative upon energization for increasing the speed of said advancingmeans for reducing the height of said first stack in said first hoppermeans, and said second control means operative upon energization fordecreasing the speed of said advancing means for increasing the heightof said first stack in said first hopper means.
 30. The apparatus ofclaim 19 wherein said antijam means comprises: a light sensitive controlmeans for sensing the position of said discharge means and operativeupon failure of said discharge means being in a predetermined positionto stop operation of said discharge means.